Stroboscopic apparatus for calibrating time indicating devices



J. M. WEBNBERGER STROBOSCOPI'C APPARATUS FOR CALIBRATING TIME INDICATING DEVICES Filed Oct. 27, l

Patented New. 3% 19% SJTRGGSCQPEC APEARATUS FOR CALI- BRATWG TIME INDICATING DEVICES Joseph M. Weinberger, Brooklyn, N. Y., assignor of one-half to Tessie Weinberger, Brooklyn,

Application October 27, 1944, Serial No. 560,686

2 Claims. 3

This invention relates to apparatus for calibrating precision instruments and more particularly to calibrating timing instruments such as clocks and watches.

An object of this invention is to provide apparatus of the above mentioned character by means of which the oscillating parts of a watch or clock to be calibrated are stroboscopically compared with similar parts of a standard watch or clock.

Another object of this invention is to provide apparatus which directly compares these oscillating parts without intermediate mechanical or electrical devices.

A further object is to provide apparatus for calibrating clocks and watches of inherent accuracy comparable to the accuracy of the instrument to be calibrated.

A still further object of this invention is to provide a device which is inexpensive and simple to manufacture, and easy to maintain.

A feature of this invention resides in the construction of the oscillating balance wheel.

Another feature resides in the construction of the stationarybottom plate.

A future feature of this invention resides in the manner of creating intermittent views of the oscillating parts of the instrument to be calibrated.

Other objects and features will become apparent from the following descriptions and the accompanying drawings in which like numerals in dicate similar parts and in which:

Fig. 1 is an underside view of the essential parts of one embodiment of this invention.

Fig. 2 is a cross section of a complete assembly of the said embodiment on line 2-4 of Fig. 1.

Fig. 3 is an enlarged section oithe oscillating.

mechanism of this invention.

Fig. 4 is a modified sectional view through another embodiment of this invention.

The former practice in watch or clock calibra tion has been to compare the watch or clock to be adjusted against a mechanism which utilizes electric apparatus (such as electric motors and amplifiers) or vibrating apparatus (such as tuning forks or piezo-electric crystals). This had been done by picking up the tick with microphones or by gauging the motion of thewatch to be calibrated with photo-electric cells, and comparing these criteria with a disc rotated by an electric motor. This method is inadequate, since even a crystal-controlled synchronous motor has 'not nearly the accuracy of a moderately-priced watch.

To properly calibrate a watch of precise manufacture, requires a standard of equal, or higher I accuracy against which it can be compared.

This invention provides a. device of such accuracy without utilizing intermediate devices which would tend to dissipate its inherent accuracy.

In its simplest embodiment, the invention comprises an oscillating balance wheel 2 having a solid disc 3 which is driven by a mainspring and barrel ii, a gear train 5 and I3 and a. lever type of escapement 6. A spiral hairspring l is attached to the staff 8 of the balance wheel and is regulated by a pair of pins 9 which restrain the motion of the hairspring. The disc of the balance wheel is provided with a slot it which passes under a corresponding slot ii in the stationary main plate I.

l The slots'in the balance wheel and in the plate are in such positions that when the balance wheel is at rest with the hairspring relaxed, the two slots are directly in line and constitute a line of sight.

When the mainspring 4 is wound up and the balance wheel 2 is oscillating, the slot iii in the balance wheel passes under the slot I l in the main plate i. Since the slot in the main plate is at the normal rest position of the balance wheel slot, it

, is also at its point of maximum angular velocity as it passes under the slot in the main plate.

Thus, if the balance wheel 2 is accurately regulated to keep correct time, as indicated by a dial it, and a pair of hands I! attached to the second gear is, the slot in the balance wheel will pass the slot in the main plate exactly five times in a second or eighteen thousand times in an hour.

The eye is placed at the main plate slot, either directly or through a system of lenses i4, and the line of sight is directed at the balance wheel it of a watch to be calibrated.

The passing of the oscillating slot under the stationary slot at high velocity, produces a series of momentary views of the balance wheel to be calibrated.

The regulator of the watch to be calibrated is moved from one side to .the other until the balance wheel it appears to stand still. At this point, the two balance wheels are exactly synchronized.

In one embodiment of this invention, Fig. 2, the

mechanism is enclosed in a case it with a window.

IT on the top for viewing the hands II. A slot is provided in the bottom of the case and the reguheld therein by means of a set screw 2 l.

The watch to be calibrated is placed on they "rupts the light beam, causing a flashing light to (all upon the balance wheel ill which maybe viewed directly from any angle. 1 1 The balance wheel ill will appear to be stationary when it is synchonized with the upper balance wheel M2. The device-is supported on a stand I ll. 1 i

The case ll may be detached from the stand ll producing a device of extreme portability which can be carried in the -pocket and used while held in the hand.

This invention completely'solves the maintenance problem of watch and clock calibrating instruments, by providing the men in the watch repairing trade with an instrument, the basic elements of which they-are competent to repair and maintain, thus making the cost of maintenance no greater than that oi an average watch.

It eliminates another annoyance to the repair man by allowing him to regulate and calibrate a watch immediately aiter repairing or assembling and prior to placing it in its case.

' By stroboscopically observing the balance wheel, directly, many faults in the watch mechanism may be detected beiore the watch is disassembled, such as: hairspring out of beat, ialtering oi the gear train, uneven delivery of power by the mainspring, and many more.

Besides being a calibrating device, this invention may act as an accurate timepiece on the watch repairers bench, thus eliminating the ne-, cessity of keeping another timepiece at hand.

I wish it distinctly understood that, while I have particularly described the simplest elements adapted to periorm the functions set forth, it is obvious that they could be subject to modifications, and various changes in form, proportion and in minor details of construction may be resorted to without departing irom the spirit or sacrificing any of the principles of the invention.

What I claim is:

l. A device for calibrating a time indicating device comprising an oscillating member and a stationary member; said oscillating member com- 4 prising a solid disc provided with a radially disposed slot; said stationary member being disposed adjacent to said oscillating member and provided with a corresponding slot; means for imparting oscillatory motion to said oscillating member;

means for regulating the rate of oscillation 01 said oscillating member; an optical system disposed along an axis through the slot in said stationary member; a numbered dial and indicating hands attached to said motion producing means; a case enclosing and containing the hereabove mentioned means; said case being provided with a window for viewing said hands and dial, a mounting to position said optical system along said axis, the case being provided with a slot for adjusting said regulating means; and a supporting stand; said stand being provided with means to detachably receive said case.

2. A device for calibrating-a time indicating device comprising an oscillating member and a stationary member; said oscillating member comprising a solid disc provided with a radially disposed slot; said stationary member being disposed parallel to said oscillating disc and provided with a corresponding slot; means for imparting oscillatory motion to said oscillating member; means for regulating the rate of oscillation of said oscillating member; an optical system disposed along an axis through the slot in said stationary member; a light source detachably-mounted on said optical system, disposed along said axisiand collimated through said optical system; a numbered dial and indicating hands attached to said motion producing means; a case enclosing and containing the hereabove mentioned means; said case being provided with a window for viewing said hands and dial, a mounting to position said optical system along said axis, and the case being provided with a slot for adjusting said regulating means; and a detachable supporting stand.

JOSEPH M. WEINBERGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 808,384 Kershaw Dec. 26, 1905 1,953,148 Young Apr. 3, 1934 1,968,859 Smith Aug. 7, 1934 

